Beta-diketone-epoxy resin reaction products useful for providing corrosion resistance

ABSTRACT

Novel compositions of matter comprising a water-dispersible reaction product of beta-diketones and epoxy material are hereby provided. The beta-diketones useful herein are those which enolize in amounts that render them sufficiently acidic and reactable with epoxy groups of the resin. The novel reaction products can be dispersed in water and they can be formulated optionally with curing agents. Ferrous metals treated with the compositions of this invention exhibit excellent corrosion-resistant properties.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to treating metallic substrates,particularly ferrous metal substrates, so as to impart corrosionresistance thereto.

2. Brief Description of the Prior Art

It is well known in the art that chromic acid and phosphatingpretreatments can be used to impart corrosion resistance to substrates.Examples of these pretreatments are the phosphating treatments whichinclude iron phosphating, mixed iron and calcium phosphating and zincphosphating. Such pretreatments may optionally be followed by a chromicacid rinse. The pretreatment operations, although employed on manyindustrial electrodeposition lines, are undesirable for a number ofreasons. First of all, pretreatments are expensive. Besides the cost ofthe chemicals themselves, a considerable capital investment is requiredfor equipment. In addition, pretreatments cause pollution problems, thesolutions of which add to their expense. Also known in the art are oniumsalts of monomers and polymers which can be used to pretreat metallicsubstrates to impart corrosion resistance.

The present invention relates to the reaction products of abeta-diketone and an epoxy material; presently said products can be usedfor the preparation of compositions which impart excellent corrosionresistance properties to substrates treated therewith.

Reference is hereby made to commonly assigned Ser. No. 193,047, filedeven date herewith, entitled "Beta-Diketone-Epoxy Resin ReactionProducts Blended With Monomeric or Polymeric Phosphonium Salts Usefulfor Providing Corrosion Resistance."

SUMMARY OF THE INVENTION

In accordance with the foregoing, the present invention encompasses anovel composition of matter comprising the reaction product of:

(A) an epoxy material, and

(B) a beta-diketone of the formula: ##STR1## wherein R₁, R₂ and R₃, eachindependently, is a hydrogen or a hydrocarbyl group preferablycontaining from about 1 to about 18 carbon atoms, selected from thegroup consisting of alkyl or aryl.

It is recognized that when R₁ or R₂, each independently, is a hydrogen,the compound according to the afore-described structure would be aketoaldehyde or a dialdehyde which could be as useful as thebeta-diketone in preparing the instant novel compositions of matter. Thecarboxyl hydrogen of the aldehyde, particularly the dialdehyde, is,however, highly reactive and may, for that matter, be less desirable.Should that reactivity be made manageable, the aldehydes would be wellsuited for the present invention.

The term "hydrocarbyl group" as used herein denotes both unsubstitutedand substituted hydrocarbons, provided that the substituent does notadversely affect the reactions of the beta-diketones or the use of theirreaction products.

The term "beta-diketone" as used herein is, therefore, intendedgenerically to classify the reacting compounds of the present inventionin accordance with the afore-described structural formula. Severally,these compounds are also referred to herein as aldehydes and ketones.Consonant therewith, the beta-diketones that are useful herein are thosewhich enolize in amounts that render them sufficiently acidic andreactable with the epoxy materials to provide the instant reactionproducts in sufficient amounts.

The present invention also encompasses water-dispersible compositionscomprising the reaction product and a water-solubilizing group.Preferably, the water-solubilizing group is a precursor of an oniumsalt. Accordingly, the water-dispersible compositions of the presentinvention comprise an onium salt; said compositions contain the reactionproduct of:

(A) an epoxy material;

(B) a beta-diketone of the formula: ##STR2## wherein R₁, R₂ and R₃, eachindependently, is a hydrogen or a hydrocarbyl group preferablycontaining from about 1 to about 18 carbon atoms, selected from thegroup consisting of alkyl or aryl; and

(C) an onium salt precursor which is an acid salt of a tertiary amine, atertiary phosphine-acid mixture, or a sulfide-acid mixture.

The methods of preparing the novel compositions of matter, and thewater-dispersible compositions thereof, particularly those comprisingthe onium salt, are encompassed by this invention. The methods of usingthe products of this invention to provide improved corrosion resistanceto ferrous metal substrates are also encompassed by the presentinvention; particularly preferred is the method of electrodeposition.

The method of providing improved corrosion resistance to a metal,particularly a ferrous metal substrate, comprises the steps of:

(1) applying to the surface of the substrate an aqueous dispersioncontaining the reaction product of:

(A) an epoxy material;

(B) a beta-diketone of the formula: ##STR3## wherein R₁, R₂ and R₃, eachindependently, is a hydrogen or a hydrocarbyl group preferablycontaining from about 1 to about 18 carbon atoms, selected from thegroup consisting of alkyl or aryl; and

(C) an onium salt precursor which is an acid salt of a tertiary amine, atertiary phosphine-acid mixture, or a sulfide-acid mixture; followed by

(2) directly coating the surface with a coating material.

It has been found that the novel compositions can be formulatedoptionally with curing agents to provide compositions with improvedproperties. Films obtained therefrom are corrosion and solventresistant; they are hard, and possess good appearance and substrateadhesion.

The metal substrates obtained by methods of this invention are alsohereby encompassed.

DETAILED DESCRIPTION

The novel compositions of this invention can be prepared by reacting anepoxy material and a beta-diketone in a manner which is set forth morefully hereinafter.

The epoxy material may be of a resin class containing at least one1,2-epoxy group. The resin may be, for example, among the generalclasses commonly referred to as polyethers, polyesters, acrylic,urethane, and the like. Although monoepoxides such as phenyl glycidylether, n-butyl glycidyl ether and the like can be utilized, it ispreferred that the epoxy material contain more than one 1,2-epoxy groupper molecule, i.e., polyepoxide. Examples of suitable polyepoxides aredescribed in U.S. Pat. Nos. 2,467,171; 2,615,007; 2,716,123; 3,030,336;3,053,855 and 3,075,999.

Particularly preferred polyepoxides are polyglycidyl ethers of cyclicpolyols, particularly polyphenols such as bisphenol A. These may beproduced by etherification of a cyclic polyol with epichlorohydrin ordichlorohydrin in the presence of alkali. Examples of cyclic polyols arebis(4-hydroxyphenyl)-2,2-propane, 4,4'-dihydroxybenzophenone,bis(4-hydroxyphenyl)-1,1-isobutane,bis(4-hydroxytertiarybutylphenyl)-2,2-propane,bis(2-hydroxynaphthyl)methane, 1,5-hydroxynaphthalene or the like. Also,polyepoxides similarly produced from epichlorohydrin and novolak-typephenol resins may be employed.

Also preferred are the acrylic polymers containing epoxy groups.Preferably, these acrylic polymers are polymers formed by copolymerizingan alpha,beta-ethylenically unsaturated epoxy-containing monomer, suchas, for example, glycidyl acrylate or methacrylate with othercopolymerizable alpha,beta-ethylenically unsaturated monomers.

Any polymerizable monomeric compound containing at least one ##STR4##preferably in terminal position, may be polymerized with the unsaturatedglycidyl compounds. Examples of such monomers include:

1. monoolefinic and diolefinic hydrocarbons;

2. halogenated monoolefinic and diolefinic hydrocarbons;

3. esters of organic and inorganic acids;

4. organic nitriles.

The acrylic polymers, their method of preparation and thecopolymerizable monomers are known in the art. Examples thereof aredisclosed by U.S. Pat. No. 3,928,156, column 4, line 40, through column6, line 68, which is herein incorporated by reference.

As set forth hereinbefore, the beta-diketones that are useful in thisinvention are those which enolize in amounts that are sufficient torender them acidic and reactable with the epoxy material. The preferredbeta-diketones have a percent of enolization of about 40 percent orhigher. In accordance with the afore-described formula, the followingare specific but non-limiting examples of the beta-diketones which areuseful herein.

When either R₁ or R₂ is hydrogen, the beta-diketones useful herein arepreferably 3-keto-1-butanol, 3-keto-1-hexanol and 3-keto-1-pentanol; andwhen both R₁ and R₂ are hydrogen, the beta-diketone useful herein ispropane dialdehyde.

When R₁ and R₂, each independently, is alkyl such as methyl, ethyl,propyl, butyl, pentyl and higher alkyl groups such as decyl, hexadecylor the like, the beta-diketones useful herein are preferably2,4-pentanedione; 2,4-hexanedione; 2,4-heptanedione;5-methyl-2,4-hexanedione; 1-cyclohexyl-1,3-butanedione; and5,5-dimethyl-1,3-cyclohexanedione.

When R₁ and R₂, each independently, is an aryl group such as phenyl,naphthyl, anthracyl, diphenyl or the like, the beta-diketones usefulherein are preferably 1-phenyl-1,3-butanedione;1-(4-biphenyl)-1,3-butanedione; and1-phenyl-5,5-dimethyl-2,4-hexanedione.

R₁ and R₂ each may be a member of a heterocycle, provided that thehetero-atom is not directly attached to the carbonyl carbon.Beta-diketones such as 1-(2-furyl)-1,3-butanedione and1-(tetrahydro-2-furyl)-1,3-butanedione are illustrative of this group ofbeta-diketones.

R₃ is more preferably a hydrogen or a lower alkyl such as methyl, ethyl,and the like; hydrogen is particularly preferred.

Typically, the beta-diketones having a percent of enolization of about40 to about 99 are particularly preferred. Accordingly,1-phenyl-1,3-butanedione is very highly preferred. Others such as2,4-pentanedione, 3-keto butyraldehyde and propane dialdehyde possess ahigh degree of enolization and would, therefore, be preferred.

In preparing the novel reaction product, the afore-describedbeta-diketones and the epoxy material are reacted, preferably in anequivalent ratio of about 0.1 to about 0.6, more preferably in anequivalent ratio of about 0.35 to about 0.45 of the beta-diketone to anequivalent of the epoxy material, in the presence of a catalyst.

Catalysts such as phosphonium salts, for example, ethyl triphenylphosphonium acetate, ethyl triphenyl phosphonium iodide and tetrabutylphosphonium acetate are present in the preparation of the novelcomposition of the present invention. The amount of catalyst ranges fromabout 0.1 to about 2 percent based on total weight of the reactants. Asolvent is not necessary in this reaction even though one is often usedin order to afford better control of the reaction. Solvents which areused in this reaction should be such as would not interfere with theenolization of the beta-diketone. The reaction is carried out over atime and temperature range which will not adversely affect theenolization of the beta-diketones. Preferably, the reaction is conductedover the temperature range of 100° to 160° C. for about 1 to 4 hours;the time and temperature, of course, depend on one another and on thespecific reactants, catalysts and other reaction conditions.

Water-solubilizing groups are used to make the novel reaction productwater-dispersible. The preferred water-solubilizing groups areprecursors of cationic groups. Preferably, the cationic groups usefulherein are onium groups such as a quaternary ammonium, phosphonium, andternary sulfonium salt. An onium salt can be prepared by reacting thenovel composition of this invention with an onium salt precursor. By theterm "onium salt precursor" herein is meant a tertiary amine-acid salt,a tertiary phosphine-acid mixture or sulfide-acid mixture. U.S. Pat.Nos. 3,962,165; 3,894,922; 3,959,106 and 3,937,679 which are hereinincorporated by reference, more fully describe the onium salt precursorsuseful in the present invention. Also, quaternary ammoniumhydroxide-containing reaction products can be used. Formation ofquaternary ammonium hydroxides is described in U.S. Pat. No. 4,081,341.

In preparing the onium salt, the epoxy-beta-diketone reaction product isprepared with residual epoxy groups in amounts which are reactable withthe onium salt precursor to form the onium salts in amounts sufficientto form a stable aqueous dispersion. By "stable" is meant the dispersionwill not sediment at room temperature after standing for 24 hours.However, if some sediment does form which can be redispersed with lowshear mixing, this also is considered to be a stable aqueous dispersion.The reaction of the onium salt precursor with the reacting novelcomposition of matter is essentially the same as the onium saltformation reactions described in the aforementioned U.S. patents whichhave been incorporated by reference.

The amount of onium salt precursor which is reacted with the novelcomposition can be reckoned from the amount of the startingbeta-diketone and the epoxy material. Accordingly, the equivalent ratioof the epoxy material to the beta-diketone to that of the onium saltprecursor is, preferably, 1.0/0.1-0.6/0.4-0.9; more preferably, theequivalent ratio is 1.0/0.35-0.45/0.55-0.65.

Even though the above-described reaction scheme for the formation of theonium salt of the novel compositions is preferred, it is, however,believed that alternate schemes could be effectively adopted.

In other embodiments, the water-solubilizing groups are amine salts suchas secondary or tertiary amine salts. They can be prepared by reactingthe novel compositions of matter with primary or secondary aminefollowed by at least partially acid neutralizing the reaction product.Examples of amines are mono- or dialkylamines such as ethylamine ordiethylamine, as well as hydroxyalkylamines such as diethanolamine.Examples of the acids are organic and inorganic acids such as lacticacid, acetic acid and phosphoric acid.

In the practice of the present invention, aqueous compositions of thenovel reaction product can be employed to impart corrosion resistanceproperties to metals, particularly ferrous metals. Preferably, theaqueous compositions are in the form of dispersions or solutions. Theconcentration of the novel reaction product in the aqueous dispersioncan be critical. The concentration will probably vary depending onapplication. If the concentration is too low, insufficient protectionmay be obtained. If the concentration is too high, corrosion resistancemay again suffer. At a lower concentration limit, the dispersion shouldcontain at least about 1 percent by weight of the novel reactionproduct; the percentage by weight being based on total weight of theaqueous dispersion. In general, an upper limit of 20 percent can berecommended. Preferably, water constitutes at least 25, preferably atleast 50 percent of the aqueous medium with the remainder, if any, beingorganic cosolvents.

The dispersions of the novel composition can be applied to the surfaceof the substrate in any convenient manner such as by immersion,spraying, or wiping the surface either at room temperature or atelevated temperature. When desirable, the aqueous dispersions can becathodically electrodeposited on substrates, under the generalconditions of electrodeposition, without compromising the corrosionresistance properties or the properties of latter applied coatings(whether electrocoated or not). It should be appreciated that when thelatter applied coating is by electrodeposition, the treated substrate(by electrodeposition) is not completely insulating.

After the application, the metal article is dried. Ferrous metalarticles treated with compositions of this invention have been found todisplay good corrosion resistance properties. They can be exposed to theatmosphere without danger of atmospheric oxidation on the surface. Afterdrying, the metal substrates can then be coated with a decorative orprotective coating.

As set forth herein, the novel compositions can be formulated, in acombination, with curing agents to provide compositions with additionalproperties. When formulated with curing agents, it is preferred that thenovel compositions also contain active hydrogens which are reactive atelevated temperatures with a curing agent. Examples of active hydrogensare hydroxyl, thiol, primary amine, secondary amine (including imine)and carboxyl, with hydroxyl being preferred.

The curing agents are those which are capable of reacting with theactive hydrogens to form a crosslinked product. Examples of suitablecuring agents are phenolic resins, aminoplasts, and blockedpolyisocyanates which are preferred.

Suitable aminoplasts for use in the invention are described in U.S. Pat.No. 3,937,679 to Bosso et al in column 16, line 3, continuing to column17, line 47, the portions of which are hereby incorporated by reference.As disclosed in the afore-mentioned portions of the '679 patent, theaminoplast can be used in combination with methylol phenol ethers. Theaminoplast curing agent usually constitutes about 1-60 and preferably5-40 percent by weight of the resinous composition based on total weightof the acid-solubilized resinous vehicle and the aminoplast.

With regard to the capped or blocked polyisocyanate curing agents, theseare described in U.S. Pat. No. 4,104,147, column 7, line 36, continuingto column 8, line 37, the portions of which are hereby incorporated byreference. Sufficient capped or blocked polyisocyanate is present in thecoating system such that the equivalent ratio of latent isocyanategroups to active hydrogens is at least 0.1:1 and preferably about 0.3 to1:1.

Aqueous compositions of the novel reaction product and a curing agentcan be applied to the surface of the substrate in any convenient mannersuch as by immersion, spraying, or wiping the surface either at roomtemperature or at elevated temperature. When desirable, the aqueouscompositions of the combination can be electrodeposited on a variety ofsubstrates. After the application, the substrate can be baked attemperatures such as 90° to 210° C. for about 1 to 30 minutes.

The aqueous compositions of the combination are suited for use on avariety of substrates. Films of appreciable build having excellentappearance and substrate adhesion are obtained when the instant aqueouscompositions are applied. It is noteworthy that the obtained films arecorrosion resistant, particularly on ferrous metal substrates.

This and other aspects of the invention are further illustrated by thefollowing examples. It is to be understood that the following examplesand other aspects of the invention described herein are not intended tobe limiting; rather, other equivalents of the invention are intended tobe covered, as well. It is to be further understood that all percentagecompositions expressed herein are parts by weight unless otherwisestated.

EXAMPLE I

This example illustrates the preparation of the novel composition of thepresent invention, and the quaternary ammonium salt derivative thereof.The following charge was used in the preparation:

    ______________________________________                                        Ingredients         Parts by Weight (Grams)                                   ______________________________________                                        EPON 1001*          500.0                                                     1,3-diphenyl-1,3-propanedione                                                                     70.8                                                      2-ethylhexanol      70.0                                                      Ethyl triphenyl phosphonium acetate                                                               1.3                                                       Dimethylethanolamine lactate                                                                      69.2                                                      Deionized water     23.4                                                      Deionized water     156.7                                                     ______________________________________                                         *EPON 1001 is a polyglycidyl ether of bisphenol A having an epoxy             equivalent of about 500 and a molecular weight of about 1000, commerciall     available from Shell Chemical Company.                                   

The EPON 1001, the diphenyl propanedione and the 2-ethylhexanol werecharged to a properly equipped reaction vessel and heated under anitrogen sparge for about an hour and twenty-five minutes, to atemperature of 92° C. The reaction mixture was allowed to cool, and at32° C. the ethyl triphenyl phosphonium acetate (catalyst) was added.Thereafter, the reaction mixture was heated to 135° C.; there was anexotherm and a resulting temperature rise to 155° C. After a slighttemperature drop to 151° C., the reaction mixture was heated to about175° C. The temperature was maintained over the range of 170° to 175° C.for an hour to a Gardner-Holdt viscosity of E, measured as a 44 percentresin solids solution in 2-butoxyethanol at 25° C.

At 90° C., a solution of the dimethylethanolamine lactate in the firstportion of water was introduced into the reaction vessel and thetemperature was maintained over the range of 80°-90° C. for two hours. Aclear brown solution was obtained which was thinned with the secondportion of water. The resulting reaction product had a solids content of72.5 percent.

The following illustrates the preparation of an electrodeposition bathusing the quaternary ammonium salt group-containing polymer prepared asdescribed above, use of the bath for electrodeposition of ferrous metalsubstrates, and the evaluation of the corrosion resistance of the coatedsubstrates.

The electrodeposition bath was prepared by mixing at room temperaturethe following mixture of ingredients:

    ______________________________________                                                               Parts by Weight                                        Ingredients            (Grams)                                                ______________________________________                                        The quaternary ammonium salt group-                                           containing polymer     310.3                                                  Deionized water        1190.0                                                 ______________________________________                                    

The electrodeposition bath (15 percent resin solids) was then used toelectrocoat iron phosphate pretreated steel substrates, zinc phosphatepretreated steel substrates, and untreated steel substrates. Thesubstrates were electrocoated at standard electrocoating conditions. Thecoatings were baked and scribed with an "X" and then placed in a saltspray chamber at 38° C. (100° F.) at 100 percent relative humidityatmosphere of 5 percent by weight aqueous sodium chloride, for a periodof 14 days. The coating and baking schedules, and the evaluation of thesubstrates in terms of the measurement of scribe creepage due tocorrosion are reported in the examples of Table 1.

                                      TABLE 1                                     __________________________________________________________________________                 Voltage at Which                                                                       Appearance of Film                                                   Electrocoated                                                                          After Baking at                                                      for 90 seconds                                                                         350° F. (177° C.)                                                         Film Thickness                                                                        Scribe                                Substrate    at 80° F. (27° C.)                                                       for 30 minutes                                                                          in mils Creepage (in mm.)                     __________________________________________________________________________    zinc phosphate pretreated                                                                  200      clear and glossy                                                                        0.06-0.08                                                                             0.0                                   steel                                                                         zinc phosphate pretreated                                                                  250      "         0.10-0.15                                                                             --                                    steel                                                                         iron phosphate pretreated                                                                  250      glossy    0.3-0.5 --                                    steel                                                                         iron phosphate pretreated                                                                  200      "         0.35    0.0                                   steel                                                                         untreated steel                                                                            200      glossy    1.2     0.0-0.6                               untreated steel                                                                            150      "         0.6     --                                    zinc phosphate pretreated                                                                  250      "         0.55    --                                    steel                                                                         untreated steel                                                                            150      "         0.6     --                                    __________________________________________________________________________

EXAMPLE II

The following illustrates the preparation of coating compositionscomprising quaternary ammonium group-containing polymers formulated withcrosslinkers, and the electrodeposition thereof.

    ______________________________________                                        Ingredients         Parts by Weight (Grams)                                   ______________________________________                                        Quaternary ammonium salt group-                                               containing polymer of Example I                                                                   310.3                                                     Crosslinker.sup.1   65.0                                                      Catalyst paste.sup.2                                                                              8.8                                                       Deionized water     1390.0                                                    ______________________________________                                         .sup.1 The crosslinker is a fully blocked 2,4toluene diisocyanate which       was prepared as follows: 2548.4 grams of 2butoxyethanol was added to the      toluene diisocyanate over a period of three hours and over a temperature      range of about 21-29° C. Thereafter, the reaction mixture was          maintained at a temperature range of 30 and 35° C. for 1 hour. The     reaction mixture was then heated up to 65-76° C. and 965.5 grams o     trimethylolpropane was added; there was an exotherm and a resulting           temperature rise to 142° C. The reaction mixture was allowed to        cool to about 130° C. within an hour, and then held at 90°      C. for another hour. The reaction mixture was thinned with 3116.9 grams o     butoxyethanol.                                                                .sup.2 The catalyst paste was a dibutyltin oxide with a quaternized epoxy     resin grinding vehicle.                                                  

The resinous composition, the crosslinker and the catalyst paste wereblended under agitation followed by the addition of the deionized water.The resulting dispersion had a 15 percent resin solids content.

This dispersion was used to electrocoat various substrates at standardelectrocoating conditions as reported in Table 2 below. The coatingswere baked and the baked coatings were scribed with an "X" and subjectedto salt spray corrosion testing as described in Example I. The coatingand baking schedules and the evaluation of substrates in terms of themeasurement of scribe creepage due to corrosion are reported in theexamples of Tables 2 and 3.

                  TABLE 2                                                         ______________________________________                                                               Appearance of                                                    Voltage at Which                                                                           Film After Bak-                                                  Electrocoated                                                                              ing at 350° F.                                                                     Film                                                 for 90 seconds                                                                             (177° C.) for                                                                      Thickness                                  Substrate at 80° F. (27° C.)                                                           30 minutes  in mils                                    ______________________________________                                        zinc phosphate                                                                          200          glossy      0.3 to 0.4                                 pretreated steel                                                              iron phosphate                                                                          200          glossy      0.45 to 0.5                                pretreated steel                                                              untreated steel                                                                         150          glossy      0.9 to 1.0                                 ______________________________________                                    

                  TABLE 3                                                         ______________________________________                                                               Appearance of                                                    Voltage at Which                                                                           Film After Bak-                                                  Electrocoated                                                                              ing at 400° F.                                                                     Film                                                 for 90 seconds                                                                             (204° C.) for                                                                      Thickness                                  Substrate at 80° F. (27° C.)                                                           20 minutes  in mils                                    ______________________________________                                        zinc phosphate                                                                          200          clear and glossy                                                                          0.15 to 0.3                                pretreated steel                                                              untreated steel                                                                         150          clear and glossy                                                                           1.2 to 1.5                                ______________________________________                                    

EXAMPLE III

This example further illustrates the use of the quaternary ammonium saltgroup-containing polymers of the present invention as pretreatmentagents for steel substrates.

The quaternary ammonium salt group-containing polymer was prepared inessentially the same manner as described in Example I and dispersed indeionized water to form a 10 percent resin solids dispersion.

Ferrous metal articles were dipped in the dispersion at room temperaturefor 2 minutes, blown dry with air, baked at 300° and 400° F. (149° and204° C.) for 5 minutes and then coated with a thermosetting acryliccoating composition sold commercially by PPG Industries, Inc. under thetrademark DURACRON 200. Coating was accomplished by drawing down toapproximately 1 mil thickness with a draw bar. The coated sample wasthen baked for 10 minutes at 400° F. (204° C.), scribed with an "X" andplaced in a salt spray chamber for salt spray corrosion testing asdescribed in Example I.

For the purposes of comparison, there were evaluated control panels inthe form of substrates which were dipped in an art-known pretreatmentagent which is an onium salt comprising the reaction product of EPON1001 and an acid salt of a tertiary amine (no beta-diketone moiety), andthen coated with DURACRON 200 as described above.

                  TABLE 4                                                         ______________________________________                                                                        Scribe                                        Composition         Substrate   Creepage                                      ______________________________________                                                            Test Panels                                               Quaternary ammonium salt of novel                                                                 Untreated steel                                                                           2.0 mm                                        composition (10% resin solids)                                                Quaternary ammonium salt of novel                                                                 Untreated steel                                                                           2.5 mm                                        composition (20% resin solids)                                                                    Control Panels                                            Quaternary ammonium salt of EPON                                                                  Untreated steel                                                                           3.0 mm                                        1001 (10% resin solids)                                                       Quaternary ammonium salt of EPON                                                                  Untreated steel                                                                           3.5 mm                                        1001 (20% resin solids)                                                       ______________________________________                                    

While the illustrative embodiments of the invention have been describedhereinabove with particularity, it will be understood that variousmodifications will be apparent to and can be readily made by thoseskilled in the art without departing from the scope or spirit of theinvention. Accordingly, it is intended that claims directed to theinvention be construed as encompassing all aspects of the inventionwhich would be treated as equivalents by those skilled in the art towhich the invention pertains.

Therefore, what is claimed is:
 1. A composition of matter comprising thereaction product of:(A) an epoxy material; and (B) a beta-diketone ofthe formula: ##STR5## wherein R₁, R₂ and R₃, each independently, is ahydrogen or a hydrocarbyl group containing from about 1 to about 18carbon atoms, selected from the group consisting of alkyl and aryl.
 2. Acomposition of matter comprising the reaction product of:(A) an epoxymaterial; and (B) a beta-diketone of the formula: ##STR6## wherein R₁,R₂ and R₃, each independently, is a hydrogen or a hydrocarbyl groupcontaining from about 1 to about 18 carbon atoms, selected from thegroup consisting of alkyl and aryl; and (C) a water-solubilizing group.3. The composition according to claim 2 wherein the water-solubilizinggroup is an onium salt precursor which is an acid salt of a tertiaryamine, a tertiary phosphine-acid mixture or a sulfide-acid mixture. 4.The composition according to claim 1 or 2, wherein the beta-diketone is2,4-pentanedione, 2,4-hexanedione, 2,4-heptanedione,1-phenyl-1,3-butanedione, 1-phenyl-5,5-dimethyl-2,4-hexanedione,1,3-diphenyl-1,3-propanedione, 1-cyclohexyl-1,3-butanedione,1-(2-furyl)-1,3-butanedione, 3-keto butyraldehyde or propane dialdehyde.5. The composition according to claim 4 wherein the beta-diketone is2,4-pentanedione or 1-phenyl-1,3-butanedione.
 6. The compositionaccording to claim 5 wherein the beta-diketone is1-phenyl-1,3-butanedione.
 7. The composition according to claim 1 or 2wherein the epoxy material is selected from the group consisting ofepoxy-containing polyethers, polyesters, acrylics and urethanes.
 8. Thecomposition according to claim 7 wherein the epoxy material is apolyglycidyl ether of cyclic polyols or an epoxy-containing acrylicpolymer.
 9. An aqueous dispersion comprising the composition of claim 2.10. The aqueous dispersion of claim 9 containing 1 to 20 percent byweight of the composition of matter; the percentage by weight beingbased on total weight of the aqueous dispersion.
 11. A process forpreparing the composition of claim 1; said process comprising: reactingan epoxy material with a beta-diketone of the formula: ##STR7## whereinR₁, R₂ and R₃, each independently, is a hydrogen or a hydrocarbyl groupcontaining from about 1 to about 18 carbon atoms, selected from thegroup consisting of alkyl and aryl, said reaction being conducted in thepresence of a phosphonium salt catalyst in an amount ranging from about0.1 to 2 percent based on total weight of the reactants.
 12. The processaccording to claim 11 wherein the phosphonium catalyst is ethyltriphenyl phosphonium acetate.
 13. A process according to claim 11wherein the epoxy material and the beta-diketone are reacted in anequivalent ratio of 1 to 0.1-0.6.
 14. A process according to claim 13wherein the equivalent ratio is 1 to 0.35-0.45.
 15. A process of claim11, further comprising the step of reacting the epoxymaterial-beta-diketone reaction product with an onium salt precursorwhich is an acid salt of a tertiary amine, a tertiary phosphine-acidmixture or a sulfide-acid mixture.
 16. A process according to claim 15wherein the equivalent ratio of epoxy to beta-diketone to onium saltprecursor is 1.0/0.1-0.6/0.4-0.9.
 17. The process according to claim 16wherein the equivalent ratio is 1.00/0.35-0.45/0.55-0.65.
 18. A methodof providing improved corrosion resistance to ferrous metal substratescomprising the steps of:(A) applying to the surface of a ferrous metalan aqueous dispersion containing:(1) the reaction product of:(i) anepoxy material; (ii) a beta-diketone of the formula: ##STR8## whereinR₁, R₂ and R₃, each independently, is a hydrogen or a hydrocarbyl groupcontaining from about 1 to about 18 carbon atoms, selected from thegroup consisting of alkyl and aryl; and (iii) an onium salt precursorwhich is an acid salt of a tertiary amine, a tertiary phosphine-acidmixture or a sulfide-acid mixture; followed by (B) directly coating thesurface with a coating material.
 19. A method of claim 18 wherein theapplication step (A) is by cationic electrodeposition.
 20. A ferrousmetal article obtained by the method of claim
 18. 21. A ferrous metalarticle obtained by the method of claim
 19. 22. An aqueous compositioncomprising:(1) the reaction product of:(A) an epoxy material: (B) abeta-diketone of the formula: ##STR9## wherein R₁, R₂ and R₃, eachindependently, is a hydrogen or hydrocarbyl group containing from about1 to about 18 carbon atoms, selected from the group consisting of alkyland aryl; and (C) an onium salt precursor which is an acid salt of atertiary amine, a tertiary phosphine-acid mixture or a sulfide-acidmixture; (2) a curing agent selected from the group consisting ofaminoplasts, blocked isocyanates, phenoplasts and mixtures thereof. 23.The composition of claim 22 wherein the curing agent is a blockedisocyanate.
 24. A method of electrocoating an electrically conductivesurface serving as a cathode which comprises passing an electric currentbetween said cathode and an anode immersed in an aqueous dispersion ofan electrodepositable composition; said composition comprising thecomposition of claim 22 or 23.